New Old Stock Replaceable Landside Heel for John Deere Moldboard Plows.
Aftermarket part number 300W.
Replaceable heel will fit John Deere plows with landside 979W used on the rear moldboard bottom (see last photo for details).
This replaceable heel is found on many older John Deere moldboard plow bottoms made prior to late 1950s. These heels are no longer in production.
See John Deere Parts Catalog called "Plow Bottoms" (PC-158) for parts breakdown for older Deere moldboard bottoms.